Wow. Pretty expensive, but then again this is a private varnish affair. I paid $160 for the 3751 San Diego excursion in June (Amfleet coaches and more expensive dome car), and even with two nights in L.A. (before and after the trip) shelled out less than Option 6 costs.
Even so I'd love to go, but can't really swing it with the Gathering so close.
EDIT: Read yesterday on the TRAINS News Wire that Santa Fe 3751 is the steam locomotive for this event too.